Little bit concerned

Hey guys over the past couple of days (TMI) I've been having light pink/brown discharge and I haven't had my period for months which is normal for me, I'm also on the pill. But over the last 2 days I've noticed brown flakey bits aswell. I've never experienced this before and I've had slight cramping but nothing major, I don't even know when my period is due because it's so irregular. I also took a pregnancy test and I'm not pregnant, does anyone know what it could be?